1. Field of the Invention
The invention relates to a method and apparatus for creating a three-dimensional object by the formation of layers of a deposited material.
2. Description of the Prior Art
Several methods have been proposed for creating three-dimensional objects by incremental buildup of thin layers. In our U.S. Pat. No. 5,126,529 we disclosed a method of producing articles by spray deposition using a series of masks to define cross sectional layers which form the article. In the method there disclosed the article is fully formed with an adjacent complimentary material that is removed after the article has been completely formed. Metal tubular shapes have been made by shape melting. Shape melting is a process whereby structural components are manufactured by depositing weld material layer-upon-layer until the desired geometry is achieved. Weld build up operations like shape melting require a preform which is generally a machined piece of metal onto which the first layer of build up is deposited. One example of this type of manufacture is disclosed in U.S. Pat. No. 3,156,968 to W. D. White, Jr.
In nearly all of the prior art methods for forming articles by incremental build up of layers, the article is first fully formed in a forming station. Then the article is moved for subsequent processing such as machining to a finished form. Cubitol in European Patent Application No. 88312323.4 discloses a system for forming plastic articles by applying layers of plastic which are cured and milled before the next layer is applied. As in other prior art layer deposition processes, the equipment used is a dedicated system which cannot be expanded to include other processing stations. In our pending U.S. patent applications Ser. Nos. 07/737,229, now U.S. Pat. No. 5,207,371, and 07/829,767 and our issued U.S. Pat. No. 5,126,529 we teach that it is often desirable to process individual layers before depositing successive layers thereon. Such processing could include heat treatment, shaping or shot peening. Hence, any system which forms articles, particularly metal articles, by incremental build up of layers should have the capability to be expanded to include additional processing stations.
In our issued patent we teach that various heads designed to provide each of the desired operations could be mounted on a movable platform so that each operation could be done without moving the workpiece as it is being made. However, this may not be practical as it will require the creation of specialized equipment. A better approach is to use and customize existing equipment such as computer numerically controlled (CNC) machines to do shaping, a heat treatment oven to provide heat treating as well as other equipment which perform other operations. Such available equipment cannot be used on a cost effective basis without automated handling of the workpiece to repeatedly place and remove the workpiece in each of the selected stations. Although automated systems have been developed which perform single operations on a part as it moves along an assembly line, or which transfers parts from one location to another, there is no system available which provides repetitive movement of the same workpiece into and out of the same operational stations.